2 Old Kustoms need some work

[willc]

 Hello, I have 2 Kustom heads that need a bit of work done. They are a K 200-1 and a metal slant face K 150-2. The K 200-1 when turned on does do the soft pop to the speakers that my working Kustoms do but no sound other than a slight hiss.      The K 150-2 blows fuses when turned on. Both of these amps have the original cords without ground pins. I have never really worked on large amps such as these but I build pedals regularly and I know how to use a multimeter. Any help I could get would be appreciated.  Thanks, Will

[DJPhil]

I dug around to find some schematics, you can probably piece most of it together from here.
You can use the block diagrams to get specific board numbers, they're listed separately in the PC section below.

K200-1
No signal from the power amp. I'd check and see if you're getting any output from the preamp board. This might just be a loose connection or dirty switching jack.

K150-2
This sounds more serious. Which fuses? An AC line fuse could mean a dead transformer, where a dead HT rail DC power rail fuse probably means a short in the power amp, likely dead output transformers transistors. (brain fart)

Ungrounded plug
This is one for the pros. I'd strongly advise converting these amps to grounded plugs, but I'm not 100% certain about how to do that with the way the power is set up so I'm giving no advice. It'd be much, much safer to use (for the guitarist and the tech) if converted.

I'm just the new guy, but the pros will want to know more, so I figured I'd help get you started.

[J M Fahey]

a dead HT rail fuse probably means a short in the power amp, likely dead output transformers.

Am I missing something here?  xP
Which HT rail?
Which output transformer?
And even if that Kustom did use one, it would be almost last in a looooooooong list of things to check.

[willc]

Thanks a lot for the link for schematics DJPhil, this is a great find. I could not find these anywhere. On the K 200 I think I may have a bad transistor on the driver board. It looks hinky so I will try to find a replacement and change it out. The 150 I really dont have a clue so I may take some time on this one. I will get back with any progress.

[DJPhil]

a dead HT rail fuse probably means a short in the power amp, likely dead output transformers.

Am I missing something here?  xP
Which HT rail?
Which output transformer?
And even if that Kustom did use one, it would be almost last in a looooooooong list of things to check.

Gah, I've had transformers on the brain lately, I meant to say transistors.  :duh
Also, I should probably have said DC power rail instead of HT rail.

Man, I've really got to take a break from reading about tube amps, I'm confusing more than just myself!  xP

[J M Fahey]

Don't worry, I am fed tube amps up my throat every day too :grr ... that's why I visit this SS haven so often. <3)